Better error messages

Author: erezsh

data_diff/diff_tables.py

@@ -85,13 +85,13 @@ class TableSegment:
 
     def __post_init__(self):
         if not self.update_column and (self.min_update or self.max_update):
-            raise ValueError("Error: min_update/max_update feature requires to specify 'update_column'")
+            raise ValueError("Error: the min_update/max_update feature requires 'update_column' to be set.")
 
         if self.min_key is not None and self.max_key is not None and self.min_key >= self.max_key:
-            raise ValueError("Error: min_key expected to be smaller than max_key!")
+            raise ValueError(f"Error: min_key expected to be smaller than max_key! ({self.min_key} >= {self.max_key})")
 
         if self.min_update is not None and self.max_update is not None and self.min_update >= self.max_update:
-            raise ValueError("Error: min_update expected to be smaller than max_update!")
+            raise ValueError(f"Error: min_update expected to be smaller than max_update! ({self.min_update} >= {self.max_update})")
 
     @property
     def _update_column(self):

data_diff/utils.py

@@ -18,6 +18,7 @@ def safezip(*args):
 
 def split_space(start, end, count):
     size = end - start
+    assert count <= size, (count, size)
     return list(range(start, end, (size + 1) // (count + 1)))[1 : count + 1]